¡Viva la Science!

We’ve known for decades that babies conceived at certain times of the year tend, on average, to be healthier than babies conceived at other times. But what the hell, right? Why should that be? By looking at the birth records for over 1.4 million children born in the 1990s and 2000s, two economists may have figured out how it happens.

Science deals with the big, messy soup of our world. Its eternal challenge lies in teasing out what’s truly connected from that which simply happens at the same time. Previous studies have shown the correlation between infants who are born in winter and a host of problems later in life, but no one knew why it was happening. Wintertime diseases? Higher winter pollution? It could’ve been almost anything. The questions were complicated by data showing that certain mothers, ones from a lower socioeconomic tier, are statistically more likely to have children with developmental and health problems. But they’re also more likely to give birth in the first half of the year. So what’s been causing what? To study the problem, scientists needed a way to control for things like a mother’s race, marital status and education level so they didn’t end up comparing apples to oranges.

Janet Currie and Hannes Schwandt, economists out of Princeton University, came up with a solution. They looked only at mothers who had given birth to more than one child—over 600,000 of them. That way, when the differences in outcomes were measured, it had more to do with when the baby was born than the particular social conditions of the mother.

What they noticed was kind of startling. For babies conceived in May, the study found more than a 10-freaking-percent increase in premature births. The average gestation length is only about half a day shorter, but it still matters. Being born prematurely is linked to all kinds of problems, including a weaker immune system, neurodevelopmental complications and impaired vision or hearing.

Clearly, this sucks and we need to find the culprit. The study’s authors think we can most likely blame the seasonal flu, which really gets roaring in January and February, when May-conceived babies are born. The 2009-2010 flu season was particularly nasty, infecting more people than usual, and corresponded to a more dramatic dip in gestation times.

Plenty more work needs to be done to see if the common winter flu is really the reason for the premature births and therefore the reason for the generally worse outcomes of babies conceived in May. Right now, it’s just an association—the outcomes could actually be caused by some other seasonal disease or by climate or temperature, which this study wasn’t able to control for. But by looking at large samples of already-existing data, Currie and Schwandt have given other researchers a strong lead for their inquiries. And knowledge inches forward once more.

¡Viva la Science!

Moths avoid bats. It’s nothing personal, just an understandable desire not to get devoured. In the perpetual evolutionary arms race between the nocturnal creatures, moths seem to have developed ears for the sole purpose of hearing bats’ echolocation cries—because if you want to avoid becoming someone’s midnight snack, getting wind of their approach is key.

Do you remember that part in Dead Poets Society where Robin Williams asks his students why language was invented? “To communicate,” suggests one. “No!” he replies, “To woo women.” Well, humans aren’t the only mammals that have a way of making everything about sex. Until recently, scientists believed that moths could hear sounds, but not produce them. Turns out, though, that most male moths make sounds when they want to engage in a little nookie. And not just any sounds, either—their calls are distinctly bat-like.

A sensory physiology researcher from the University of Southern Denmark, along with colleagues from the University of Tokyo, has been studying two different species of moths to find out exactly how sound is used for courtship. It’s not quite the same for everyone.

In the Asian corn borer, a moth much prettier than it sounds, males make a call that’s indistinguishable from a bat’s hunting cry. Females instinctively freeze at the sound, making it harder for the bats to find them. But in Asian corn borer society, immobility apparently equals consent, because when a female holds still, that’s when the magic of reproduction can happen.

On the other hand, male Japanese lichen moths also make sounds like bats gone a’hunting. But the females of that species aren’t fooled—they can tell the difference between a bat and a suitor. The sound the males make, then, has evolved into a specific mating call.

“The acoustic communication between bats and moths is a textbook example of the interaction between predator and prey,” says Annemarie Surlykke, the researcher from Denmark. “However, our studies show how such a system can evolve, so also moths use their ability to hear and produce sounds to communicate sexually and that they have developed many different ways of doing it. It is a beautiful example of evolutionary diversity.”

If you were wondering how moths can make sounds like bats without attracting their mortal enemies, the key seems to be volume. Moths essentially whisper their calls while only inches apart, whereas bats are pretty much just screaming through the night sky. Spooky! Since we humans aren’t equipped to hear any of it, you’ll just have to imagine what sweet nothings moths murmur to one another.

¡Viva la Science!

Researchers using data from the European Space Agency's Cluster spacecraft have found evidence that a “plasmaspheric wind” is releasing a kilogram (over two pounds) of plasma from the plasmasphere into the magnetosphere every second.

I swear you’re not reading an X-Men comic. Supervillains do not appear to be involved. Yet.

The plasmasphere is a region of dense, cold plasma that surrounds the Earth. Filled with charged particles, it’s shaped like a donut and forms the inner part of the magnetosphere, the area around our planet controlled by the magnetic field.

The existence of plasmaspheric wind was theorized over two decades ago, but it’s difficult to detect. It requires fancy instrumentation and detailed measurements of moving particles in the plasmasphere. Now, the four Cluster spacecraft have provided ion measurements from the plasmasphere that support the plasmaspheric wind theory.

We need to understand what’s going on in the plasmasphere because of its effect on things like satellites, GPS and traveling astronauts. Presumably, we also need to keep one step ahead of Magneto.

¡Viva la Science!

Maybe you've heard this a jillion times: Core strengthening is vital if you want to avoid injury. But is it true? A new study doesn't conclusively say one way or the other, but it sure casts some doubt on the incrediblycommon assertion.

In the study, released in the journal Physical Therapy, 1,100 soldiers aged 18 to 35 were divided into two groups. One group used a core stabilization exercise program that lacked sit-ups, while the other used a traditional exercise program that included bent-knee sit-ups. The point was to compare how the two programs affected the rate of musculoskeletal injury.

Why the focus on sit-ups?

Despite longstanding tradition and the widespread popularity of sit-ups, it has been postulated that this exercise results in increased lumbar spine loading, potentially increasing the risks of injury and low back pain (LBP). Specifically, sit-ups produce large shear and compressive forces on intervertebral disks and across the lumbar spine. Increased muscle activation anteriorly results in both initial hyperextension and subsequent hyperflexion of the lumbar spine, contributing to large compressive forces during sit-ups.

Sit-ups have long been an important yardstick by which the US Army measures physical health. But if they're causing injuries, or failing to prevent injuries that core strengthening could prevent, that might need to change.

The results, though, didn't show any massive difference in injuries between the two groups. “There were no differences in the percentages of soldiers with musculoskeletal injuries. There also were no differences in the numbers of days of work restriction for musculoskeletal injuries overall or specific to the upper extremity.”

It’s worth nothing that the results for the two groups weren't identical. Soldiers who completed the traditional exercise program did have more days of work restriction than the other group if their injury was to the low back.

As much as we all like studies that conclusively prove broad truths, the reality is that what we “know” tends to advance in teensy increments. This study is one thread in a much larger tapestry. What it tells us, though, is that sit-ups might not be the bogeyman and core strengthening might not be quite the miracle each has been portrayed as—as usual, more studies are needed.

¡Viva la Science!

Rising carbon dioxide levels—and oh boy, do we haz them—lead to lower pH in our oceans. The lower the pH, the more acidic the water. Coral reefs, underwater structures notoriously unwilling to relocate, are stuck dealing with the result. A new paper shows that coral reefs that have been exposed to acidic waters are less dense and more fragile.

Marine scientist and paper co-author Adina Paytan points out that it could’ve been worse. “The good news is that they don't just die,” she says, in what one can only imagine to be a hollowly perky tone of voice. “They are able to grow and calcify, but they are not producing robust structures.”

Fortunately, what she’s not saying is that the whole wide world of coral has gone rickety. Scientists, being scientists, work hard to gather data that lets them make predictions about what will happen. In this case, the study focused on coral located near underwater springs off of Mexico’s Yucatan Peninsula, where the ocean water becomes naturally more acidic.

Because, though they can simulate conditions in a laboratory, scientists can’t be deliberately acidifying coral environments in the wild, now can they? By looking at a place where coral is already surviving in conditions of higher acidity, the paper’s authors found a site “where nature is already doing the experiments for us,” explains Don Rice, program director in the National Science Foundation's (NSF) Division of Ocean Sciences.

For Paytan, the results mix not-terrible news with a concise course of action. "We need to protect corals from other stressors, such as pollution and overfishing. If we can control those, the impact of ocean acidification might not be as bad."